def read_tagged_sentence(f):
    line = f.readline()
    if not line:
        return None
    sentence = []
    while line and (line != "\n"):
        line = line.strip().decode("utf-8")
        word, tag = line.split("\t", 2)
        sentence.append( (word, tag) )
        line = f.readline()
    return sentence

def read_tagged_corpus(filename):
    sentences = []
    with open(filename) as f:
        sentence = read_tagged_sentence(f)
        while sentence:
            sentences.append(sentence)
            sentence = read_tagged_sentence(f)
    return sentences